Plate exchanger problems

[duramaxman05]

I use a 20 plate exchanger for my domestic hot water. It works great. But every year I have a problem with my woodstove gaining water. Thats the only place it can gain water. So I contacted the people I bought it from and I am going to send this one back when I get my new one so they can see why it's doing what it's doing. Anyone else have any ideas? I send off a water sample every year and add boiler treatment as needed. My house water pressure is around 75psi(exchanger is suppose to be good for 150psi, I have put a pressure regulator for main water supply and also added an expansion tank. I'm thinking corrosion or electrolysis.

 

[maple1]

Every year? Like, since it was new? Has to be a manufacturing defect if so. How much water transfer are we talking? You don't have a fill valve plumbed in too?

 

[maple1]

Also if it is corrosion related I would suspect the DHW side, not the boiler side. Maybe your water supply is slightly acidic? Our pressure runs 25-40.

 

[duramaxman05]

We installed our boiler in 2014. The first one lasted like 4 years. The second 2years and 1 every year since. I have tested the our domestic water and the ph was good. I need to check it again. I do have a fill valve I have check it and it isn't leaking. The amount of water the boiler gains, I'm not sure. We have a portage and main bl28-40 and it only holds 90 gallon. When it's gets to the full mark, I drain it out to the add mark when I know it's gaining water. Otherwise I keep it in the middle. I would say somewhere between 10-20 gallon. It takes about 2 weeks to do so. Boiler pressure is around 10psi

 

[ABMax24]

Galvanic corrosion? You're not connecting the copper heat exchanger to steel fittings are you?

Otherwise I'd be looking at the autofill/fill valve.

 

[duramaxman05]

Never heard of galvanic corrosion. I will check into that. The plate exchanger is copper and stainless. The threaded fittings on the exchanger are stainless. Sharkbite fittings on the stove side and galvanized reducers to copper on the domestic water side. I think anyways. I will have to take a picture of it.

 

[maple1]

I would never use galvanized anything anywhere on a heating or domestic water system.

 

[duramaxman05]

Here is a picture of my setup. What needs to be done? I will replace all fittings if needed be. I just ordered another plate exchanger so I want make this one last. What kind of fittings should I use?

 

[Tonty]

Those galvanized fittings should be replaced with brass or something besides galvanized. Or find something called a dielectric union and insert that. The zinc in the galvanized fittings reacts with the copper and causes rust. Although it is kind of surprises me that it would only last one year. There may be something else, but this would be a place to start.

 

[Tonty]

If you have any of the old exchangers sitting around, could you make up some fittings and pressure test them with air or water when they aren’t on the boiler and see if/where they leak? My boiler has a different style than that, so I’m not sure if that’s an option. But maybe it’s pretty obvious to you, if you have changed several of them and it stops your problem for awhile when you do.

 

[duramaxman05]

If you have any of the old exchangers sitting around, could you make up some fittings and pressure test them with air or water when they aren’t on the boiler and see if/where they leak? My boiler has a different style than that, so I’m not sure if that’s an option. But maybe it’s pretty obvious to you, if you have changed several of them and it stops your problem for awhile when you do.

I have 2 of them here that had the same problem. I may do what you said and see what happens. I am also going to send the one back to the company so they check it out. It's supposed to have a "lifetime warranty".

 

[maple1]

Here is a picture of my setup. What needs to be done? I will replace all fittings if needed be. I just ordered another plate exchanger so I want make this one last. What kind of fittings should I use?

View attachment 288638

I'd get the same fittings except stainless, not galvanized. Supply place here has a decent supply of stainless fittings. If I couldn't find stainless I'd get brass.

Edit: Actually, I'd use pex adaptors on the dhw side and replace the copper with pex back as far as convenient.

 

[ABMax24]

Don't use stainless either, copper and stainless steels together are also susceptible to galvanic corrosion.

Garbage all those galvanized fittings and replace with copper or brass.

 

[Case1030]

We installed our boiler in 2014. The first one lasted like 4 years. The second 2years and 1 every year since. I have tested the our domestic water and the ph was good. I need to check it again. I do have a fill valve I have check it and it isn't leaking. The amount of water the boiler gains, I'm not sure. We have a portage and main bl28-40 and it only holds 90 gallon. When it's gets to the full mark, I drain it out to the add mark when I know it's gaining water. Otherwise I keep it in the middle. I would say somewhere between 10-20 gallon. It takes about 2 weeks to do so. Boiler pressure is around 10psi

The Portage&Main are open systems. How are you running 10psi?

 

[maple1]

Don't use stainless either, copper and stainless steels together are also susceptible to galvanic corrosion.

Garbage all those galvanized fittings and replace with copper or brass.

But if the plate exchanger is stainless, there would have to be a transition somewhere? I have also read that dielectric connections also aren't really needed or worthwhile on a heating system.

 

[ABMax24]

But if the plate exchanger is stainless, there would have to be a transition somewhere? I have also read that dielectric connections also aren't really needed or worthwhile on a heating system.

That's right, I was under the assumption that it was a copper exchanger, that one appears to be stainless. In this case I'd just use Brass fittings as they are compatible with both copper and 300 series stainless.

We're definitely taught in school to use dielectric unions between metals like steel and copper, or at the very least use a brass fitting between the 2 metals.

 

[Tonty]

I would understand that brass would be less reactive with stainless than copper. It depends, from what I’ve read, on the type of stainless. If it were mine, I think I would make a transition between the two with brass. I’ve never been happy with dielectric unions on anything, but I suppose they must have there place.

Something of interest to read:

Galvanic corrosion - Wikipedia

en.wikipedia.org

 

[duramaxman05]

The Portage&Main are open systems. How are you running 10psi?

The pump is pumping 10psi

 

[hedge wood]

I would replace those galvanized fitting with copper when you replace it. When I look up your brand of heat exchanger its made in China that's probably your problem. I have been working around flat plate heat exchangers for well over 25 years and seen very few fail. I have five on my Garn system since 2009 and have had zero issues with them. I like to use only flat plate brand. I have pretty nasty domestic water and haven't had any issues with that one either.

 

[duramaxman05]

I would replace those galvanized fitting with copper when you replace it. When I look up your brand of heat exchanger its made in China that's probably your problem. I have been working around flat plate heat exchangers for well over 25 years and seen very few fail. I have five on my Garn system since 2009 and have had zero issues with them. I like to use only flat plate brand. I have pretty nasty domestic water and haven't had any issues with that one either.

I am definitely going to put different fittings on it. I already have one on order so it will be the same one unfortunately. Freaking China made crap. Its hard to find anything descent anymore. I will look into the brand you use.

 

[maple1]

I have had a 20 plate flat plate since 2012 with no issues, that I know of. I dont know where it was made. I suspect China as well. But I think I got it from Outdoor Furnace Supply. Who is or was a forum advertiser.

 

[Tonty]

I am definitely going to put different fittings on it. I already have one on order so it will be the same one unfortunately. Freaking China made crap. Its hard to find anything descent anymore. I will look into the brand you use.

If you think our China made stuff is junk, you should see the China made in third world countries. We lived in Zimbabwe, Africa for four years. They called that stuff “zhing-zhong”, and it was truly not much good. One store had two hair clippers, same name brand, looked identical, but one was U.S. spec and one not U.S. spec. There was a huge difference in quality. 😵‍💫

 

[duramaxman05]

This is the first one I lasted 4 or 5 years

 

[duramaxman05]

My new plate exchanger came in today. Going to pick up new fittings and install tomorrow.

 

[ABMax24]

Do you flush your system at the same time?

Just thinking there might still be ions/contaminants floating around in there that might be part of the issue.